Recently, with exhaustion of fossil energy and concern about environmental pollution, there is an increasing interest in electric products that work on electrical energy, not fossil energy.
Hence, with the increasing development and consumption of mobile devices, electric vehicles, hybrid vehicles, power storage systems, uninterrupted power supplies, or the like, the consumption of secondary batteries as an energy source are drastically increasing and their demands are diverse. To satisfy various demands, studies are actively being conducted on batteries composed of secondary cells.
Meanwhile, high voltage and large capacity batteries are required for electric vehicles or hybrid vehicles. Thus, a high voltage and large capacity battery mounted in a vehicle has an explosion hazard from an accident such as vehicle collision. That is, there is a concern about not only a direct damage caused by vehicle collision but also a secondary accident occurring from collision, for example, ignition or explosion of a battery. Particularly, electric vehicles or hybrid vehicles using high voltage and large capacity batteries have a greater risk of battery ignition or explosion. Accordingly, solutions to battery explosion in the event of vehicle collision have been proposed in the battery-related technical field.
As a related art, Korean Patent Publication No. 10-2012-0042986 discloses an automotive battery safety system. The automotive battery safety system is characterized in that battery safety equipment is activated when vehicle collision is sensed. The battery safety equipment described in the related art discloses i) a battery cooling device using compressed gas, ii) a device which electrically separates a battery, and iii) a discharge resistor.
However, i) the battery cooling device using compressed gas needs a separate gas tank and has a disadvantage of having to periodically check the gas pressure. Also, an amount of compressed gas stored may be insufficient for cooling based on the capacity of the gas tank. ii) The battery separation device has a disadvantage of being unable to control a vehicle after a collision accident because it completely separates a battery. iii) The discharge resistor needs a time to discharge a battery during which the battery cannot be cooled.
A variety of traditional battery safety systems have been disclosed, but have the above disadvantages. Particularly, the battery safety system using the cooling device according to the related art has a risk of explosion during cooling when the battery maintains a high voltage and a large capacity, and the battery safety system using the discharge resistor is problematic in that the battery has an ignition or explosion hazard due to being unable to cool rapidly.
Therefore, there is a need for research on a new type of battery safety apparatus that cools a battery, and at the same time, reduces a voltage and/or a capacity of the battery in the event of a car accident such as vehicle collision.